[PATCH] generic/740: set env for mkfs.exfat and mkfs.ntfs

[PATCH] generic/740: set env for mkfs.exfat and mkfs.ntfs

[David Timber]

Foreign filesystem detection is added in exfatprogs version 1.4.1. To
maintain backward compatibility, mkfs.exfat refuses to format the device
only when it's run from terminal with a tty associated to it.

This is similar to how e2fsprogs work around the issue. However,
with exfatprogs, this behaviour can be overridden with the special
environment variable EXFAT_TTY_OVERRIDE to simulate shell invocation by
user.

mkfs.ntfs from NTFS-3G userland package refuses to format the target
if it's backed by a "real" device but not a partition to maintain
compatibility with Windows. When formatting the scratch device in NTFS
for testing, this behaviour has to be overridden so that any type of
blockdev can be used as a scratch device.

Signed-off-by: David Timber <dxdt@dev.snart.me>
---
 tests/generic/740 | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/tests/generic/740 b/tests/generic/740
index ce55200f..89822480 100755
--- a/tests/generic/740
+++ b/tests/generic/740
@@ -28,6 +28,20 @@ _require_block_device "${SCRATCH_DEV}"
 # not all the FS support zoned block device
 _require_non_zoned_device "${SCRATCH_DEV}"
 
+mkfs_preop=""
+mkfs_preargs=""
+mkfs_postargs=""
+
+case "$FSTYP" in
+	exfat)
+		# Some fsprogs were slow to implement foreign fs detection.
+		# For backward compatibility, mkfs.exfat refuses to format only
+		# when run from a tty. This env var should override the
+		# behaviour if supported.
+		mkfs_preop="EXFAT_TTY_OVERRIDE=1"
+		;;
+esac
+
 echo "Silence is golden."
 for fs in `echo ${MKFS_PROG}.* | sed -e "s:${MKFS_PROG}.::g"`
 do
@@ -60,8 +74,10 @@ do
 		postargs=2000
 		;;
 	ntfs)
-		# "quick" format that doesn't zero the entire device
-		postargs="--quick"
+		# "quick" format that doesn't zero the entire device. Use -F so
+		# that NTFS-3G mkfs formats the volume even if the scratch
+		# blockdev is not a partition.
+		postargs="-QF"
 		;;
 	reiser4)
 		preop="echo y |"
@@ -83,7 +99,7 @@ do
 		# next, ensure we don't overwrite it
 
 		echo "=== Attempting $FSTYP overwrite of $fs..." >>$seqres.full
-		${MKFS_PROG} -t $FSTYP $SCRATCH_DEV >>$seqres.full 2>&1
+		eval $mkfs_preop ${MKFS_PROG} -t $FSTYP $mkfs_preargs $SCRATCH_DEV $mkfs_postargs >>$seqres.full 2>&1
 
 		[ $? -eq 0 ] && echo "Failed - overwrote fs type ${fs}!"
 	else
-- 
2.54.0

Re: [PATCH] generic/740: set env for mkfs.exfat and mkfs.ntfs

[Christoph Hellwig]

On Wed, Jun 17, 2026 at 01:57:31AM +0900, David Timber wrote:
> +case "$FSTYP" in
> +	exfat)

Please don't indent the matches in case statements (yes, we probably
have a few legacy cases that do it, but copy the right ones :))

> +		# Some fsprogs were slow to implement foreign fs detection.
> +		# For backward compatibility, mkfs.exfat refuses to format only
> +		# when run from a tty. This env var should override the
> +		# behaviour if supported.

I don't get the 'Some fsprogs' part here.  Maybe just drop that line?

>  	ntfs)
> -		# "quick" format that doesn't zero the entire device
> -		postargs="--quick"
> +		# "quick" format that doesn't zero the entire device. Use -F so
> +		# that NTFS-3G mkfs formats the volume even if the scratch
> +		# blockdev is not a partition.
> +		postargs="-QF"

Why does this switch from the long to the short form quick argument?

>  		echo "=== Attempting $FSTYP overwrite of $fs..." >>$seqres.full
> -		${MKFS_PROG} -t $FSTYP $SCRATCH_DEV >>$seqres.full 2>&1
> +		eval $mkfs_preop ${MKFS_PROG} -t $FSTYP $mkfs_preargs $SCRATCH_DEV $mkfs_postargs >>$seqres.full 2>&1

Maybe add a line break to keep the line at a reasonable length.

Also in doubt split the exfat and ntfs changes as they seem entirely
unrelated.